Internal combustion engine for portable power generating equipment

Abstract

An internal combustion engine for portable power generating equipment includes a camshaft assembly having an integral oil pump at one end thereof. The camshaft, which is preferably formed of two dissimilar materials, is mounted for axial movement in response to increased oil pressure so as to provide automatic oil pressure regulation. Structure is provided for reducing engine compression at low speeds to reduce cranking resistance during starting. Speed control is provided by a stepper motor coupled through a cam to the engine throttle. The cam is shaped so as to counteract the non-linear relationship between throttle position and engine power and speed so as to provide a desired relationship between the position of the stepper motor and the engine power and speed.

We claim: 
     
       1. In an internal combustion engine having a cylinder, a piston mounted for reciprocation within the cylinder, a crankshaft operatively coupled through a connecting rod to the piston for rotational movement in response to reciprocation of the piston, one or more valves associated with the cylinder, and a camshaft operatively coupled to the crankshaft for actuating the valve, the improvement comprising forming the camshaft in two separate pieces, the first piece being formed of a first material and defining at least one cam lobe, the second piece being formed of a powdered metal and defining a gear for receiving motive power therethrough, said first and second pieces being joined to form a unitary structure having a cam lobe portion formed of said first material and a gear portion formed of said powdered metal.